1. Field of the Invention
The present invention relates to microcomputer systems for data processing and for the high-speed location of blocks of characteristics stored in the data file storage zone of a working storage device, and more particularly to such systems in which the blocks of characteristics are several bytes in length.
2. The Prior Art
In many applications of microcomputer systems, such as radio switching, it is expedient to work with blocks of characteristics. In a radio switching system, each subscriber is assigned a specific combination of signals (representative of letters and numerals) which is stored as a characteristic block. On the basis of the stored characteristic blocks, it can be determined whether a given subscriber is still located within radio exchange range. If a subscriber, upon being interrogated, does not answer within a specific interval of time, his characteristic block is erased from the working storage. Naturally, it is also possible to store not only the characteristic block but also additional associated data, for example, charges. The use of characteristic blocks is in no way confined to exchange devices but is suitable for data files of all kinds.
The "Micro-Computer User's Manual SAB8085" published by Siemens, Order No. B1825.101, discloses on Pages A1-6 and A1-7 a microprocessor system with a block hunting device. Here the hunting or searching process takes place by way of a DMA (direct memory access) controller, in which the searching process involves a comparison which is carried out byte by byte. When the byte search for has been located, the comparator emits a signal which terminates the searching process. The circuit described in the Siemens publication referred to above is particularly suitable for locating blocks of characteristics in which the block is only one byte in length. If a block of characteristics comprises several bytes, the bytes must be checked individually and in turn. However, in the case of extensive data files, with characteristic blocks having a length of several bytes, the process described in the Siemens publication referred to above is not feasible, because of the excessive requirements for searching time.